Artemis II is now on a loop­ing path that will carry the crew around the far side of the Moon and back again. It is the first time since 1972 that hu­mans have trav­elled out­side of the Earth’s or­bit.

Legal in­tern Raj Gambhir was the prin­ci­pal au­thor of this post.

The Trump ad­min­is­tra­tion has re­stricted the First Amendment right to record law en­force­ment by is­su­ing an un­prece­dented na­tion­wide flight re­stric­tion pre­vent­ing pri­vate drone op­er­a­tors, in­clud­ing pro­fes­sional and cit­i­zen jour­nal­ists, from fly­ing drones within half a mile of any ICE or CBP ve­hi­cle.

In January, EFF and me­dia or­ga­ni­za­tions in­clud­ing The New York Times and The Washington Post re­sponded to this bla­tant in­fringe­ment of the First Amendment by de­mand­ing that the FAA lift this flight re­stric­tion. Over two months later, we’re still wait­ing for the FAA to re­spond to our let­ter.

The First Amendment guar­an­tees the right to record law en­force­ment. As we have seen with the ex­tra­ju­di­cial killings of George Floyd, Renée Good, and Alex Pretti, cap­tur­ing law en­force­ment on cam­era can drive ac­count­abil­ity and raise aware­ness of po­lice mis­con­duct.

The FAA reg­u­larly is­sues tem­po­rary flight re­stric­tions (TFRs) to pre­vent peo­ple from fly­ing into des­ig­nated air­space. TFRs are usu­ally is­sued dur­ing nat­ural dis­as­ters, or to pro­tect ma­jor sport­ing events and gov­ern­ment of­fi­cials like the pres­i­dent, and in most cases last mere hours.

Not so with the re­stric­tion num­bered FDC 6/4375, which started on January 16, 2026. This TFR lasts for 21 months—un­til October 29, 2027—and cov­ers the en­tire na­tion. It pre­vents any per­son from fly­ing any un­manned air­craft (i.e., a drone) within 3000 feet, mea­sured hor­i­zon­tally, of any of the “facilities and mo­bile as­sets,” in­clud­ing “ground ve­hi­cle con­voys and their as­so­ci­ated es­corts,” of the Departments of Defense, Energy, Justice, and Homeland Security. Violators can be sub­ject to crim­i­nal and civil penal­ties, and risk hav­ing their drones seized or de­stroyed.

In prac­ti­cal terms, this TFR means that any­one fly­ing their drone within a half mile of an ICE or CBP agen­t’s car (a DHS “mobile as­set”) is li­able to face crim­i­nal charges and have their drone shot down. The prac­ti­cal un­fair­ness of this TFR is un­der­scored by the fact that im­mi­gra­tion agents of­ten use un­marked rental cars, use cars with­out li­cense plates, or switch the li­cense plates of their cars to carry out their op­er­a­tions. Nor do they pro­vide prior warn­ing of those op­er­a­tions.

While the FAA as­serts that the TFR is grounded in its law­ful au­thor­ity, the flight re­stric­tion not only vi­o­lates mul­ti­ple con­sti­tu­tional rights, but also the agen­cy’s own reg­u­la­tions.

First Amendment vi­o­la­tion. As we high­lighted in the let­ter, nearly every fed­eral ap­peals court has rec­og­nized the First Amendment right of Americans to record law en­force­ment of­fi­cers per­form­ing their of­fi­cial du­ties. By sub­ject­ing drone op­er­a­tors to crim­i­nal and civil penal­ties, along with the po­ten­tial de­struc­tion or seizure of their drone, the TFR pun­ishes—with­out the re­quired jus­ti­fi­ca­tions—law­ful record­ing of law en­force­ment of­fi­cers, in­clud­ing im­mi­gra­tion agents.

Fifth Amendment vi­o­la­tion. The Fifth Amendment guar­an­tees the right to due process, which in­cludes be­ing given fair no­tice be­fore be­ing de­prived of lib­erty or prop­erty by the gov­ern­ment. Under the flight re­stric­tion, ad­vanced no­tice is­n’t even pos­si­ble. As dis­cussed above, drone op­er­a­tors can’t know whether they are within 3000 hor­i­zon­tal feet of un­marked DHS ve­hi­cles. Yet the TFR al­lows the gov­ern­ment to cap­ture or even shoot down a drone if it flies within the TFR ra­dius, and to im­pose crim­i­nal and civil penal­ties on the op­er­a­tor.

Violations of FAA reg­u­la­tions. In is­su­ing a TFR, the FAA’s own reg­u­la­tions re­quire the agency to “specify[] the haz­ard or con­di­tion re­quir­ing” the re­stric­tion. Furthermore, the FAA must pro­vide ac­cred­ited news rep­re­sen­ta­tives with a point of con­tact to ob­tain per­mis­sion to fly drones within the re­stricted area. The FAA has sat­is­fied nei­ther of these re­quire­ments in is­su­ing its na­tion­wide ban on drones get­ting near gov­ern­ment ve­hi­cles.

We don’t be­lieve it’s a co­in­ci­dence that the TFR was put in place in January 2026, at the height of the Minneapolis anti-ICE protests, shortly af­ter the killing of Renée Good and shortly be­fore the shoot­ing of Alex Pretti. After both of those tragedies, civil­ian record­ings played a vi­tal role in con­tra­dict­ing the gov­ern­men­t’s false ac­count of the events.

By pun­ish­ing civil­ians for record­ing fed­eral law en­force­ment of­fi­cers, the TFR helps to shield ICE and other im­mi­gra­tion agents from scrutiny and ac­count­abil­ity. It also dis­cour­ages the ex­er­cise of a key First Amendment right. EFF has long ad­vo­cated for the right to record the po­lice, and ex­er­cis­ing that right to­day is more im­por­tant than ever.

Finally, while record­ing law en­force­ment is pro­tected by the First Amendment, be aware that of­fi­cers may re­tal­i­ate against you for ex­er­cis­ing this right. Please re­fer to our guid­ance on safely record­ing law en­force­ment ac­tiv­i­ties.

Federal data shows the tech gi­ant filed for over 3,000 for­eign worker visas as it cuts thou­sands of American jobs.

Federal data shows the tech gi­ant filed for over 3,000 for­eign worker visas as it cuts thou­sands of American jobs.

Submit your up­dates here. ›

Oracle, the soft­ware com­pany head­quar­tered in Austin, Texas, has filed thou­sands of pe­ti­tions for H-1B visas in the past two fis­cal years, even as it lays off thou­sands of American work­ers as part of a broader or­ga­ni­za­tional shift. Federal data shows Oracle filed for 2,690 H-1B visas in fis­cal year 2025 and 436 so far in fis­cal year 2026, to­tal­ing over 3,100 visa re­quests.

The H-1B visa pro­gram al­lows com­pa­nies to tem­porar­ily em­ploy for­eign work­ers with spe­cial­ized skills, of­ten in the tech in­dus­try. Critics ar­gue the pro­gram is used to re­place American work­ers with cheaper for­eign la­bor, while sup­port­ers say it helps fill cru­cial tal­ent gaps. Oracle’s visa fil­ings amid mass lay­offs raise ques­tions about the com­pa­ny’s mo­ti­va­tions and the broader de­bate over the H-1B pro­gram’s im­pact on the American work­force.

According to U. S. Citizenship and Immigration Services data, Oracle America Inc. filed for 2,690 H-1B visas for fis­cal year 2025 and 436 so far for fis­cal year 2026. This comes as Oracle re­port­edly be­gan lay­ing off thou­sands of em­ploy­ees this week, with work­ers re­ceiv­ing let­ters stat­ing ‘today is your last work­ing day.’ The com­pany has not pro­vided pub­lic com­ment on the lay­offs or the H-1B visa fil­ings.

* Oracle filed for 2,690 H-1B visas for fis­cal year 2025, which cov­ers October 1, 2024 to September 30, 2025.

* Oracle filed for 436 H-1B visas so far for fis­cal year 2026, which runs from October 1, 2025 to September 30, 2026.

The full im­pact of Oracle’s lay­offs and H-1B visa fil­ings re­mains to be seen, as the com­pany has not pro­vided de­tailed pub­lic com­ment on its work­force changes and for­eign worker hir­ing plans.

The take­away

Oracle’s ac­tions raise con­cerns about the com­pany po­ten­tially re­plac­ing American work­ers with cheaper for­eign la­bor through the H-1B visa pro­gram, even as it un­der­goes a ma­jor or­ga­ni­za­tional shift. This case high­lights the on­go­ing de­bate over the H-1B pro­gram’s im­pact on the U.S. work­force and the need for greater trans­parency from com­pa­nies uti­liz­ing the pro­gram.

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Official web­sites use .gov A .gov web­site be­longs to an of­fi­cial gov­ern­ment or­ga­ni­za­tion in the United States.

Secure .gov web­sites use HTTPS A lock () or https:// means you’ve safely con­nected to the .gov web­site. Share sen­si­tive in­for­ma­tion only on of­fi­cial, se­cure web­sites.

OpenClaw be­fore 2026.3.28 con­tains a priv­i­lege es­ca­la­tion vul­ner­a­bil­ity in the /pair ap­prove com­mand path that fails to for­ward caller scopes into the core ap­proval check. A caller with pair­ing priv­i­leges but with­out ad­min priv­i­leges can ap­prove pend­ing de­vice re­quests ask­ing for broader scopes in­clud­ing ad­min ac­cess by ex­ploit­ing the miss­ing scope val­i­da­tion in ex­ten­sions/​de­vice-pair/​in­dex.ts and src/​in­fra/​de­vice-pair­ing.ts.

NVD en­rich­ment ef­forts ref­er­ence pub­licly avail­able in­for­ma­tion to as­so­ci­ate

vec­tor strings. CVSS in­for­ma­tion con­tributed by other sources is also

dis­played.

CVSS 4.0 Severity and Vector Strings:

Denotes Vulnerable Software

Are we miss­ing a CPE here? Please let us know.

OpenClaw be­fore 2026.3.28 con­tains a priv­i­lege es­ca­la­tion vul­ner­a­bil­ity in the /pair ap­prove com­mand path that fails to for­ward caller scopes into the core ap­proval check. A caller with pair­ing priv­i­leges but with­out ad­min priv­i­leges can ap­prove pend­ing de­vice re­quests ask­ing for broader scopes in­clud­ing ad­min ac­cess by ex­ploit­ing the miss­ing scope val­i­da­tion in ex­ten­sions/​de­vice-pair/​in­dex.ts and src/​in­fra/​de­vice-pair­ing.ts.

My phone beeped. It was 10pm in the mid­dle of a busy week in book pub­lish­ing — London Book Fair 2025. My col­leagues were alert­ing me to a tweet by Andy Stone, a spokesman at Meta (formerly Facebook). It was short and to the point: “This rul­ing af­firms that Sarah Wynn-Williams’s false and defam­a­tory book should never have been pub­lished.”

The book in ques­tion was Careless People, a grip­ping and ex­plo­sive ac­count of Sarah’s time work­ing at Facebook as di­rec­tor of global pub­lic pol­icy from 2011 to 2017. The “ruling” to which Stone re­ferred was made by a US ar­bi­tra­tor af­ter Meta sought an in­junc­tion, ban­ning Sarah from pro­mot­ing her own book or say­ing any­thing neg­a­tive about Meta, po­ten­tially for ever.

I am Sarah’s ed­i­tor at Pan Macmillan. Like all pub­lish­ers, I typ­i­cally work be­hind the scenes to am­plify the voices of our au­thors. I am only writ­ing this be­cause she can­not.

The day af­ter Stone’s March 12 tweet, Careless People was due to be re­leased in the UK. Drawing on doc­u­men­tary ev­i­dence, it de­tails a stag­ger­ing range of al­le­ga­tions, in­clud­ing sex­ual ha­rass­ment, the de­lib­er­ate ma­nip­u­la­tion of vul­ner­a­ble teenagers and the com­pa­ny’s al­leged com­plic­ity in geno­cide. It also ac­cuses Facebook of hypocrisy re­gard­ing cen­sor­ship, al­leg­ing the com­pany worked “hand in glove” with the Chinese Communist Party. But it was per­haps the per­sonal por­traits of top ex­ec­u­tives that were most damn­ing.

The rul­ing, awarded with­out proper no­tice by an emer­gency ar­bi­tra­tor (a non-court me­di­a­tor that is part of the American Arbitration Association), ac­tu­ally said noth­ing about the truth or oth­er­wise of Sarah’s dev­as­tat­ing claims in her book. It made no men­tion of defama­tion. Instead, it re­lied on a non-dis­par­age­ment clause in her sev­er­ance agree­ment with Facebook to si­lence her. Which it did, from March 13, 2025, her pub­li­ca­tion day. We could still pub­lish the book, but our au­thor could not talk about it. Sarah was left in an un­prece­dented and un­en­vi­able po­si­tion for an au­thor, rem­i­nis­cent of an Orwellian night­mare. Today, she has to po­lice her own speech, fac­ing fines of $50,000 for every state­ment that could be seen to be “negative or oth­er­wise detri­men­tal” to Meta.

Despite her re­sid­ing in the UK, the terms of the or­der are so broad that they ex­tend to the pri­vacy of her own home, even when speak­ing to her own fam­ily. The $50,000 fines could ap­ply in­di­vid­u­ally to the many state­ments in her book too. She faces fi­nan­cial ruin from a multi-tril­lion-dol­lar com­pany seek­ing mil­lions of dol­lars she does­n’t have, as part of the on­go­ing le­gal process which is yet to con­clude — and all for re­veal­ing in­for­ma­tion that is in the pub­lic in­ter­est. She is an award-win­ning, best­selling au­thor. But her voice has been taken away.

In some ways, Meta’s in­ter­ven­tion did us, as her pub­lish­ers, a favour. Careless People was al­ways likely to be a best­seller. But when read­ers re­alised that Meta was try­ing to sup­press it, the book be­came a global phe­nom­e­non. To date we’ve sold al­most 200,000 copies. It has re­ceived rave re­views and cre­ated a me­dia firestorm for its rev­e­la­tions. But also be­cause of the bit­ter irony in Meta’s le­gal ac­tion to si­lence Sarah.

In January 2025, only a few months be­fore it was pub­lished, chief ex­ec­u­tive Mark Zuckerberg had stated that it was “time to get back to our roots around free ex­pres­sion”. They had aban­doned the use of in­de­pen­dent fact-check­ers, claim­ing they were bi­ased and en­cour­aged cen­sor­ship. Yet, in truth, free speech only mat­tered when it was­n’t used to in­ter­ro­gate Meta it­self.

Companies like Meta are wealth­ier than some coun­tries and more pow­er­ful too. They own the tech­nol­ogy be­hind the mod­ern world. We have pub­lished books about highly in­flu­en­tial in­di­vid­u­als be­fore and, in my ex­pe­ri­ence, they tend not to like it and have well re­sourced le­gal teams be­hind them. But Meta’s lead­er­ship had a dif­fer­ent level of power. So Careless People was brought to pub­li­ca­tion in an aura of se­crecy and (it turns out jus­ti­fied) para­noia.

A very small team worked on the book. We com­mu­ni­cated on en­crypted chan­nels and when­ever it was dis­cussed, those not in­volved had to leave the room. There was a ru­mour in our of­fice that it might be Taylor Swift’s mem­oir. Sarah did­n’t even tell her mum she had writ­ten it be­fore the news was made pub­lic.

Usually, we an­nounce our books to re­tail­ers many months in ad­vance. This is so they can build pre-or­ders and sort the lo­gis­tics of get­ting them to book­shops in good time. After all, they deal with thou­sands of new ti­tles re­leased every week. With Careless People, the months rolled by and yet we kept de­lay­ing our an­nounce­ment, con­scious of po­ten­tial at­tempts to quash it. Our in­cred­i­ble sales team man­aged to con­vince re­tail­ers — in­clud­ing a num­ber of su­per­mar­kets — to stock the book with­out even telling them what it was, but re­tail­ers’ pa­tience had lim­its. When we fi­nally did an­nounce the book, it was just a week be­fore pub­li­ca­tion (again un­prece­dented) and we had no idea what to ex­pect.

Sarah went on a pub­lic­ity blitz. She did her first and only print in­ter­view with Rosamund Urwin for this pa­per. In a whirl­wind 24 hours, she jet­ted off to New York for an in­ter­view with NBC, fly­ing back overnight for an in­ter­view the fol­low­ing day with the BBC in our of­fices. She had­n’t slept and ar­rived straight from the air­port at dawn. One of the world’s most sig­nif­i­cant whistle­blow­ers show­ered in our base­ment and used a tote bag from our chil­dren’s de­part­ment as a towel. Who says that pub­lish­ing is­n’t glam­orous?

But the pub­lic­ity tour stopped only a week af­ter it had be­gun, on the day of our pub­li­ca­tion and the rul­ing. The au­dio­book, recorded in se­cret be­fore the gag or­der took ef­fect, soon be­came the only way to hear Sarah speak. And the book? Well, Meta’s spokesman, Stone, called it “a mix of out-of-date and pre­vi­ously re­ported claims about the com­pany and false ac­cu­sa­tions about our ex­ec­u­tives”. Yet not every­one agreed.

In April 2025, Sarah was called to give ev­i­dence to a US Senate sub­com­mit­tee, al­leg­ing that she saw Meta ex­ec­u­tives “repeatedly un­der­mine US na­tional se­cu­rity and be­tray American val­ues” by pro­vid­ing the Chinese Communist Party with ac­cess to the data of Meta users. The chair­man, Republican Senator Josh Hawley, con­cluded the hear­ing by say­ing: “I have a mes­sage to Mark Zuckerberg, as well. It’s time for you to tell the truth. You should come to this com­mit­tee and take an oath and sit where Ms Wynn-Williams is sit­ting now and an­swer this ev­i­dence. Stop try­ing to si­lence her.” He is yet to ap­pear al­most a year later.

In the UK, Careless People was also sent to all MPs by the Molly Rose Foundation, a char­ity set up to pre­vent sui­cide in peo­ple un­der 25. Its chief ex­ec­u­tive Andy Burrows said: “Her claims that Meta cyn­i­cally ex­ploited the well­be­ing of teenage girls to grow its ad­ver­tis­ing rev­enue will deeply dis­turb par­ents and put the con­duct of Meta’s lead­er­ship un­der the spot­light.”

Last Wednesday, Mark Zuckerberg was forced to give ev­i­dence in a land­mark so­cial me­dia ad­dic­tion trial in Los Angeles, which has the po­ten­tial to set new prece­dents, hold­ing so­cial me­dia com­pa­nies legally re­spon­si­ble for their im­pact on chil­dren and ado­les­cents.

While Zuckerberg de­fends his record in court, Sarah sits in London, legally gagged. She can­not com­ment on the trial. She can­not dis­cuss the very book that helped spark this global con­ver­sa­tion. With the pa­per­back to come out this Thursday, Sarah’s fate re­mains un­cer­tain and the le­gal process rum­bles on slowly in the US. Yet she re­tains her fight­ing spirit, as well as the dry hu­mour that is richly on dis­play in Careless People. I feel hugely ho­n­oured to have worked with her and have gained a new ap­pre­ci­a­tion of the per­sonal sac­ri­fices that whistle­blow­ers make for the greater good.

Careless People ex­posed what Sarah termed a cul­ture of “lethal care­less­ness”. Meta’s re­sponse —ruthless and chill­ing — proved her point bet­ter than any mar­ket­ing cam­paign ever could. But while they have stopped her from speak­ing, they could not stop you from read­ing. And that is why books that hold power to ac­count are more im­por­tant than ever.

Mike Harpley is pub­lisher, non-fic­tion at Pan, part of Pan Macmillan, and the ed­i­tor of Careless People: A Story of Where I Used to Work by Sarah Wynn-Williams, pub­lished in pa­per­back by Pan on February 26, £10.99.

Careless People by Sarah Wynn-Williams (Pan Macmillan £10.99). To or­der a copy go to times­book­shop.co.uk. Free UK stan­dard P&P on or­ders over £25. Special dis­count avail­able for Times+ mem­bers.

Nicholas Carlini, a re­search sci­en­tist at Anthropic, re­ported at the [un]prompted AI se­cu­rity con­fer­ence that he used Claude Code to find mul­ti­ple re­motely ex­ploitable se­cu­rity vul­ner­a­bil­i­ties in the Linux ker­nel, in­clud­ing one that sat undis­cov­ered for 23 years.

Nicholas was as­ton­ished at how ef­fec­tive Claude Code has been at find­ing these bugs:

We now have a num­ber of re­motely ex­ploitable heap buffer over­flows in the Linux ker­nel. I have never found one of these in my life be­fore. This is very, very, very hard to do.With these lan­guage mod­els, I have a bunch.

What’s most sur­pris­ing about the vul­ner­a­bil­ity Nicholas shared is how lit­tle over­sight Claude Code needed to find the bug. He es­sen­tially just pointed Claude Code at the Linux ker­nel source code and asked, “Where are the se­cu­rity vul­ner­a­bil­i­ties?”

Nicholas uses a sim­ple script sim­i­lar to the fol­low­ing:

The script tells Claude Code that the user is par­tic­i­pat­ing in a cap­ture the flag cy­ber­se­cu­rity com­pe­ti­tion, and they need help solv­ing a puz­zle.

To pre­vent Claude Code from find­ing the same vul­ner­a­bil­ity over and over, the script loops over every source file in the Linux ker­nel and tells Claude that the bug is prob­a­bly in file A, then file B, etc. un­til Claude has fo­cused on every file in the ker­nel.

In his talk, Nicholas fo­cused on a bug that Claude found in Linux’s net­work file share (NFS) dri­ver which al­lows an at­tacker to read sen­si­tive ker­nel mem­ory over the net­work.

Nicholas chose this bug to show that Claude Code is­n’t just find­ing ob­vi­ous bugs or look­ing for com­mon pat­terns. This bug re­quired the AI model to un­der­stand in­tri­cate de­tails of how the NFS pro­to­col works.

The at­tack re­quires an at­tacker to use two co­op­er­at­ing NFS clients to at­tack a Linux NFS server:

(1) - Client A does a three-way hand­shake with the NFS server to be­gin NFS op­er­a­tions.

(2) - Client A re­quests a lock file. The server ac­cepts, and the client ac­knowl­edges the ac­cep­tance.

(3) - Client A ac­quires the lock and de­clares a 1024-byte owner ID, which is an un­usu­ally long but le­gal value for the owner ID. The server grants the lock ac­qui­si­tion.

The at­tacker then spins up a sec­ond NFS client, Client B, to talk to the server:

(4) Client B does a three-way hand­shake with the NFS server to be­gin NFS op­er­a­tions, same as (1) above.

(5) Client B re­quests ac­cess to the same lock file as Client A from (2). The NFS server ac­cepts, and the client ac­knowl­edges the ac­cep­tance.

(6) Client B tries to ac­quire the lock, but the NFS server de­nies the re­quest be­cause client A al­ready holds the lock.

The prob­lem is that at step (6), when the NFS server tries to gen­er­ate a re­sponse to client B deny­ing the lock re­quest, it uses a mem­ory buffer that’s only 112 bytes. The de­nial mes­sage in­cludes the owner ID, which can be up to 1024 bytes, bring­ing the to­tal size of the mes­sage to 1056 bytes. The ker­nel writes 1056 bytes into a 112-byte buffer, mean­ing that the at­tacker can over­write ker­nel mem­ory with bytes they con­trol in the owner ID field from step (3).

Fun fact: Claude Code cre­ated the ASCII pro­to­col di­a­grams above as part of its ini­tial bug re­port.

This bug was in­tro­duced in the Linux ker­nel in March 2003:

The bug is so old, I can’t even link di­rectly to it be­cause it pre­dates git, which was­n’t re­leased un­til 2005.

Nicholas has found hun­dreds more po­ten­tial bugs in the Linux ker­nel, but the bot­tle­neck to fix­ing them is the man­ual step of hu­mans sort­ing through all of Claude’s find­ings:

I have so many bugs in the Linux ker­nel that I can’t re­port be­cause I haven’t val­i­dated them yet… I’m not go­ing to send [the Linux ker­nel main­tain­ers] po­ten­tial slop, but this means I now have sev­eral hun­dred crashes that they haven’t seen be­cause I haven’t had time to check them.

I searched the Linux ker­nel and found a to­tal of five Linux vul­ner­a­bil­i­ties so far that Nicholas ei­ther fixed di­rectly or re­ported to the Linux ker­nel main­tain­ers, some as re­cently as last week:

What’s strik­ing about Nicholas’ talk was how rapidly large lan­guage mod­els have im­proved at find­ing vul­ner­a­bil­i­ties. Nicholas found these bugs us­ing Claude Opus 4.6, which Anthropic re­leased less than two months ago. He tried to re­pro­duce his re­sults on older AI mod­els, and dis­cov­ered that Opus 4.1 (released eight months ago) and Sonnet 4.5 (released six months ago) could find only a small frac­tion of what Nicholas found us­ing Opus 4.6:

I ex­pect to see an enor­mous wave of se­cu­rity bugs un­cov­ered in the com­ing months, as re­searchers and at­tack­ers alike re­al­ize how pow­er­ful these AI mod­els are at dis­cov­er­ing se­cu­rity vul­ner­a­bil­i­ties.

››››Gold over­takes U. S. Treasuries as the world’s largest for­eign re­serve as­set in 2026 — can gold chal­lenge the U.S. dol­lar’s dom­i­nance and hold its ground?

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Gold over­takes U. S. Treasuries as the world’s largest for­eign re­serve as­set in 2026 — can gold chal­lenge the U.S. dol­lar’s dom­i­nance and hold its ground?Gold over­takes U.S. Treasuries as the world’s largest for­eign re­serve as­set in 2026: Gold has crossed a his­toric mile­stone. In 2026, it over­took U.S. Treasuries to be­come the world’s largest for­eign re­serve as­set by value. Central banks now hold close to $4 tril­lion worth of gold, dri­ven by record buy­ing and a sharp price rally above $4,500 an ounce in 2025. According to data tracked by the World Gold Council, of­fi­cial gold re­serves reached roughly 36,000 met­ric tons by early 2026. At cur­rent prices, that stock­pile is now worth more than for­eign-held U.S. Treasuries.Listen to this ar­ti­cle in sum­ma­rized for­mat­Gold over­takes U.S. Treasuries as the world’s largest for­eign re­serve as­set in 2026 — will gold de­throne the U.S. dol­lar as the global re­serve an­chor long term?Gold over­takes U.S. Treasuries as the world’s largest for­eign re­serve as­set in 2026: Gold has climbed past U.S. gov­ern­ment bonds to be­come the largest for­eign re­serve as­set held by cen­tral banks world­wide, mark­ing a ma­jor shift in global fi­nan­cial mar­kets. The to­tal value of gold held by for­eign of­fi­cial in­sti­tu­tions is now ap­proach­ing $4 tril­lion, ex­ceed­ing roughly $3.9 tril­lion in U.S. Treasury hold­ings for the first time since 1996.

The mile­stone comes amid a record rally in gold prices, broad­en­ing geopo­lit­i­cal risk, and ag­gres­sive bul­lion ac­cu­mu­la­tion by cen­tral banks. Gold ended 2025 up more than 70%, briefly top­ping $4,500 an ounce in late December be­fore main­tain­ing high lev­els in early January 2026.

The jour­ney to $4,500 gold was paved by global in­sta­bil­ity. Throughout 2025, es­ca­lat­ing Middle East ten­sions cre­ated a “fear pre­mium” that in­vestors could not ig­nore. Conflict in key en­ergy cor­ri­dors re­minded the world of the fragility of the global sup­ply chain. Simultaneously, do­mes­tic pol­icy un­cer­tainty in the United States—ranging from debt ceil­ing de­bates to shifts in trade tar­iffs—shook con­fi­dence in the green­back.

Central bank gov­er­nors in emerg­ing mar­kets, par­tic­u­larly in Asia and Eastern Europe, were the pri­mary dri­vers of this de­mand. These in­sti­tu­tions added over 1,100 tonnes of gold to their vaults in 2025 alone. They viewed the metal as a crit­i­cal shield against in­fla­tion and po­ten­tial as­set freezes. As the U.S. na­tional debt crossed the $38 tril­lion thresh­old, the “safe-haven” ap­peal of Treasuries weak­ened, leav­ing gold as the last stand­ing pil­lar of fi­nan­cial sta­bil­ity.

Central banks have been ac­cu­mu­lat­ing gold at per­sis­tent high lev­els over the past sev­eral years. Holdings now to­tal roughly 36,000–37,000 tonnes, plac­ing gold’s share of global of­fi­cial re­serves at around 25–27%, a his­toric high com­pared with Treasuries and ma­jor fiat cur­ren­cies.

This mas­sive ac­cu­mu­la­tion is dri­ven by sev­eral fac­tors:

Diversification away from dol­lar‑de­nom­i­nated as­sets amid fears of pol­icy un­pre­dictabil­ity and fis­cal strain in the United States.Safe‑haven de­mand in an era of grow­ing geopo­lit­i­cal ten­sion and mar­ket volatil­ity.Cen­tral banks from emerg­ing mar­kets and ad­vanced economies alike have joined the buy­ing trend. Nations such as China, India, Turkey, and Qatar reg­u­larly ap­pear among the top pur­chasers. In some cases, these pur­chases re­flect ef­forts to re­duce de­pen­dence on for­eign cur­rency re­serves that may be vul­ner­a­ble to sanc­tions or rapid ex­change‑rate swings.

Historically, cen­tral bank gold pur­chases av­er­aged around 473 tonnes an­nu­ally over much of the 2010s. Recent an­nual pur­chases have more than dou­bled that pace, sig­nal­ing a struc­tural shift in global re­serve man­age­ment.

Gold’s rise as a re­serve as­set has been re­in­forced by in­ten­si­fy­ing geopo­lit­i­cal flash­points world­wide, which have dri­ven safe‑haven de­mand from both of­fi­cial buy­ers and pri­vate in­vestors.

In 2025, re­newed con­flict be­tween Israel and Iran, in­clud­ing airstrikes and mil­i­tary es­ca­la­tions, pushed in­vestors to­ward gold. Safe‑haven bids emerged as mar­kets feared broader re­gional in­sta­bil­ity.

In early 2026, U.S. spe­cial forces cap­tured Venezuelan President Nicolás Maduro, height­en­ing geopo­lit­i­cal ten­sion and prompt­ing re­newed in­ter­est in gold and other havens. Precious met­als, in­clud­ing gold and sil­ver, saw sharp price ad­vances in the days fol­low­ing the op­er­a­tion.

Meanwhile, Iran is ex­pe­ri­enc­ing deep un­rest and eco­nomic tur­moil, with wide­spread protests and ris­ing in­fla­tion. These fac­tors are com­pound­ing risks in the Middle East and re­in­forc­ing gold’s role as a hedge against un­cer­tainty.

Analysts note that these con­di­tions — rather than any sin­gle event — are cu­mu­la­tively re­shap­ing re­serve strate­gies. When cen­tral banks per­ceive height­ened risk of con­flict, sanc­tions, or in­sta­bil­ity, they tend to boost hold­ings of as­sets with no coun­ter­party risk. Gold, un­like bonds or fiat cur­ren­cies, can­not de­fault or be frozen un­der sanc­tion regimes.

Despite this dra­matic shift, the U.S. dol­lar re­mains the world’s dom­i­nant re­serve cur­rency, ac­count­ing for an es­ti­mated 45–58% of to­tal for­eign ex­change re­serves de­pend­ing on val­u­a­tion meth­ods.

Gold’s over­tak­ing of Treasuries as a re­serve as­set does not yet mean it has sur­passed the dol­lar over­all, but it does high­light struc­tural shifts in how na­tions man­age risk and di­ver­si­fi­ca­tion.

Economists note that while Treasury se­cu­ri­ties re­main prized for liq­uid­ity and deep sec­ondary mar­kets, po­lit­i­cal po­lar­iza­tion, fis­cal deficits, and mon­e­tary pol­icy un­cer­tain­ties may be prompt­ing re­serve man­agers to re­duce ex­po­sure to debt in­stru­ments.

This trend is re­in­forced by fore­casts that safe-haven as­sets like gold are poised for con­tin­ued struc­tural de­mand in 2026 and be­yond. Recent es­ti­mates sug­gest gold prices could ap­proach or ex­ceed $4,800 per ounce on sus­tained cen­tral bank buy­ing and weaker dol­lar trends.

The shift in re­serve com­po­si­tion car­ries broad im­pli­ca­tions for fi­nan­cial mar­kets, in­vestors, and pol­i­cy­mak­ers:

Reserve di­ver­si­fi­ca­tion: Countries may opt for a bal­anced re­serve base in­clud­ing gold, Treasuries, and other as­sets to en­sure both liq­uid­ity and safety.Cur­rency mar­kets: Reduced re­liance on U.S. debt could grad­u­ally dampen de­mand for dol­lar-de­nom­i­nated se­cu­ri­ties, widen­ing global cur­rency di­ver­si­fi­ca­tion.In­fla­tion and in­ter­est rates: Persistent gold de­mand may in­di­cate cau­tious sen­ti­ment on in­fla­tion and real yields, in­flu­enc­ing cen­tral bank pol­icy.In­vestor psy­chol­ogy:Gold’s ris­ing sta­tus re­in­forces con­fi­dence in tra­di­tional store-of-value as­sets dur­ing times of un­cer­tainty.As we move deeper into 2026, the ques­tion is whether gold can hold its ground. Most mar­ket an­a­lysts be­lieve the rally has fur­ther to run. Forecasts from ma­jor in­vest­ment banks sug­gest gold could av­er­age $5,000 per ounce by the end of the year. The ra­tio­nale is sim­ple: the fac­tors that drove the 2025 surge—geopo­lit­i­cal fric­tion and high debt—have not been re­solved.

Sustained buy­ing is ex­pected to con­tinue as cen­tral banks aim for a 20% to 25% gold-to-re­serve ra­tio. Many de­vel­op­ing na­tions still hold less than 10% of their wealth in gold. If these coun­tries con­tinue their di­ver­si­fi­ca­tion strat­egy, the in­flux of cap­i­tal could keep prices el­e­vated for years. For the first time in the mod­ern era, gold is not just a backup; it is the pri­mary en­gine of global wealth preser­va­tion.

Q: Why has gold over­taken U.S. Treasuries as the largest for­eign re­serve as­set?

A: Foreign cen­tral banks now hold nearly $4 tril­lion in gold, ex­ceed­ing $3.9 tril­lion in Treasuries. Rising gold prices, geopo­lit­i­cal ten­sions, and di­ver­si­fi­ca­tion away from dol­lar as­sets are dri­ving this his­toric shift. Central banks aim to re­duce risk and pro­tect re­serves from fis­cal and geopo­lit­i­cal un­cer­tain­ties.

Q: Which coun­tries are lead­ing in gold re­serve ac­cu­mu­la­tion?

A: Major buy­ers in­clude China, India, Turkey, and Qatar, among oth­ers. Central banks have in­creased an­nual pur­chases to more than 900–1,000 tonnes, more than dou­ble the 2010s av­er­age. This re­flects a global trend of re­bal­anc­ing re­serves to­ward gold for sta­bil­ity and safe-haven pro­tec­tion.

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Iranian strikes have ren­dered two Amazon Web Services avail­abil­ity zones “hard down” in Dubai and Bahrain and the com­pany ex­pects them to be “unavailable for an ex­tended pe­riod,” ac­cord­ing to in­ter­nal Amazon com­mu­ni­ca­tion re­viewed by Big Technology.

Within Amazon Web Services, the strikes have ren­dered so much dam­age that em­ploy­ees have been ad­vised to de­pri­or­i­tize both re­gions.

“These two re­gions con­tinue to be im­paired, and ser­vices should not ex­pect to be op­er­at­ing with nor­mal lev­els of re­dun­dancy and re­siliency,” an in­ter­nal memo read. “We are ac­tively work­ing to free and re­serve as much ca­pac­ity as pos­si­ble in the re­gion for cus­tomers, and ser­vices should be scaled to the min­i­mal foot­print re­quired to sup­port cus­tomer mi­gra­tion.”

Reached for com­ment, an Amazon spokesper­son pointed Big Technology to an Amazon blog post about the dis­rup­tions. “We con­tinue to sup­port af­fected cus­tomers, help­ing them to mi­grate to al­ter­nate AWS Regions, with a large num­ber al­ready suc­cess­fully op­er­at­ing their ap­pli­ca­tions from other parts of the world,” the post read. “As this sit­u­a­tion evolves, and as we have ad­vised be­fore, we re­quest those with work­loads in the af­fected re­gions con­tinue to mi­grate to other lo­ca­tions.”

With the war now near­ing its sixth week, Iran has made Amazon in­fra­struc­ture in the Gulf an eco­nomic tar­get and is now eye­ing its peers. Amazon’s Bahrain fa­cil­i­ties have been hit mul­ti­ple times, in­clud­ing a Wednesday strike that caused a fire. And its fa­cil­i­ties in the UAE also sus­tained mul­ti­ple hits. The IRGC is threat­en­ing mul­ti­ple other U. S. tech gi­ants, in­clud­ing Microsoft, Google, and Apple.

Amazons in­fra­struc­ture in Bahrain and Dubai each have three ‘availability zones’ or clus­ters of com­pute. Both Bahrain and Dubai have a zones that are “hard down” and and “impaired but func­tion­ing.” per the in­ter­nal com­mu­ni­ca­tion.

“We do not have a time­line for when DXB and BAH will re­turn to nor­mal op­er­a­tions,” the in­ter­nal post said.

Greg Brockman is the President and co-founder of OpenAI. Brockman joins Big Technology to dis­cuss OpenAI’s prod­uct strat­egy, the rise of its com­ing su­per app, and why he be­lieves AI is en­ter­ing a new take­off phase. Tune in to hear Brockman ex­plain OpenAI’s bet on the GPT rea­son­ing model tree over video gen­er­a­tion, what the “Spud” pre-train­ing run means for up­com­ing mod­els, and why he be­lieves AGI is 70-80% achieved. We also cover the com­pet­i­tive land­scape, the eco­nom­ics be­hind OpenAI’s $110 bil­lion in­fra­struc­ture bet, and pub­lic skep­ti­cism to­ward AI. Hit play for one of the most re­veal­ing con­ver­sa­tions yet about where AI is headed and what it means for every­one.

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This was writ­ten on March 1, 2026

I think it is in­cred­i­bly cool that we can change a Linux sys­tem into a net­work­ing de­vice. But have you ever won­dered:

What are we chang­ing when we turn a Linux sys­tem into a router or switch? What are we chang­ing if we make a rasp­berry pi into a WiFi ac­cess point? How sig­nif­i­cant is the sys­tem per­for­mance mon­i­tor­ing change? What are the gates we have to change to en­able packet for­ward­ing and pro­cess­ing?

I’m go­ing to start out with a nar­ra­tive ex­pla­na­tion of the changes that turn a Linux sys­tem into a WiFi ac­cess point and then I’ll show the com­mands for im­ple­ment­ing it.

I have a cog­ni­tive bias: I think of net­work­ing de­vices and com­put­ers as dif­fer­ent things. This is be­cause the com­mand line ex­pe­ri­ence on net­work­ing gear is dif­fer­ent than what you ex­pe­ri­ence on servers/​hosts. On servers and work­sta­tions: you tend to fo­cus a lot on ob­jects on the file sys­tem. On net­work­ing gear, you’re spend­ing most of your time work­ing with run­ning processes di­rectly. Commands and in­ter­ac­tion ob­jec­tives on net­work­ing gear is very dif­fer­ent than those on hosts.

I sus­pect a lot of other peo­ple who have worked in net­work­ing have sim­i­lar feel­ings about net­work­ing ap­pli­ances ver­sus host op­er­at­ing sys­tems. This might be spe­cific to my jour­ney. But for bet­ter or worse, I felt that net­work­ing was dif­fer­ent than gen­eral com­put­ing. It is­n’t. If you know net­work­ing, you can make Linux do net­work­ing things if you make 7 changes.

To ac­ti­vate packet pro­cess­ing and for­ward­ing in the Linux Kernel, you start by chang­ing the Kernel’s con­fig­u­ra­tion for net­work­ing. Every Android de­vice that vends a per­sonal WiFi hotspot makes the same gen­eral changes.

Let’s as­sume we have a Linux ma­chine with a sin­gle net­work in­ter­faces. A packet ar­rives on the ex­ter­nally fac­ing in­ter­face. The Network Interface Card (NIC) sig­nals an in­ter­rupt and the dri­ver pulls the frame into a ring buffer in ker­nel mem­ory via Direct Memory Access (DMA), where the hard­ware writes data into RAM with­out Central Processing Unit (CPU) in­volve­ment. The ker­nel’s net­work­ing stack picks the frame up from there, strips the Ethernet header, and ex­am­ines the Internet Protocol (IP) des­ti­na­tion ad­dress.

At that point the ker­nel con­sults its rout­ing table. If the des­ti­na­tion ad­dress matches one of the ma­chine’s own in­ter­faces, the packet trav­els up through the net­work stack to a lis­ten­ing socket, to a process wait­ing to han­dle it. If the des­ti­na­tion ad­dress matches no lo­cal in­ter­face and IP for­ward­ing is dis­abled, the ker­nel drops the packet and in­cre­ments a counter in /proc/net/snmp.

The de­fault be­hav­ior of Linux is the end of the line for a packet: the ker­nel can­not for­ward the packet to an­other host. We need to make changes to the sys­tem if we want to en­able rout­ing. We also need an­other nic to send across net­work in­ter­faces. A work­sta­tion is a host, not a router.

Now imag­ine that same sys­tem with two NICs (aka dual-homed)- how do we get closer to rout­ing pack­ets?

A router’s role is to for­ward the pack­ets our sin­gle-homed host drops by de­fault. Let’s ex­plore each of the steps that move the ker­nel from a work­sta­tion’s con­ser­v­a­tive pos­ture as a host into a router that routes pack­ets, mod­i­fies packet head­ers, and fil­ters traf­fic be­tween in­ter­faces.

In the Linux ker­nel, a hook is a des­ig­nated in­ter­cep­tion point in a code path where ex­ter­nal func­tions can reg­is­ter them­selves to ex­e­cute. Think of it as a slot in an as­sem­bly line: the main process pauses at pre­de­fined points and runs every func­tion that has reg­is­tered at that slot, in pri­or­ity or­der. Each reg­is­tered func­tion can in­spect, mod­ify, ac­cept, or drop the item pass­ing through. Hooks let the ker­nel sep­a­rate its core packet-pro­cess­ing logic from pol­icy de­ci­sions like fil­ter­ing and ad­dress trans­la­tion. The ker­nel de­fines where the hooks are; ad­min­is­tra­tors and tools like nfta­bles de­cide what code runs at each one. The ker­nel im­ple­ments hooks as ar­rays of func­tion point­ers stored in struc­tures like struct nf_hook_en­tries. At each hook point, the ker­nel it­er­ates the ar­ray via nf_hook_s­low(), pass­ing each reg­is­tered call­back a pointer to the pack­et’s sk_buff struc­ture.

Earlier, I made ref­er­ence to “The ker­nel’s net­work­ing stack.” Just what does that mean?

A packet ar­rives at the NIC. The dri­ver places it in mem­ory and the ker­nel’s net­work­ing stack processes it through sev­eral or­dered stages. At de­fined points along this path, the ker­nel passes the packet through net­fil­ter, a hook-based frame­work built di­rectly into the ker­nel’s net­work­ing code.

Netfilter hooks are func­tion pointer ar­rays reg­is­tered in­side the ker­nel’s packet pro­cess­ing path. At each hook point, the ker­nel it­er­ates through every reg­is­tered func­tion in pri­or­ity or­der, pass­ing a pointer to the pack­et’s socket buffer (sk_buff). Each reg­is­tered func­tion can ac­cept, drop, mod­ify, or queue the packet. Userspace tools like nfta­bles reg­is­ter call­back func­tions at these hooks by send­ing com­mands through a netlink socket, a ker­nel-user­space Inter-Process Communication (IPC) chan­nel de­signed for net­work­ing con­fig­u­ra­tion.

You can ob­serve net­fil­ter’s ac­tiv­ity at run­time. nft list rule­set shows all cur­rently reg­is­tered ta­bles and chains. con­ntrack -L shows the live con­nec­tion track­ing table. For deeper in­spec­tion, perf trace or bpf­trace can at­tach probes to ker­nel func­tions like nf_hook_s­low (the func­tion the ker­nel calls when it it­er­ates hook call­backs), let­ting you watch in­di­vid­ual packet de­ci­sions in real time.

The five stan­dard hook points are:

After PREROUTING, the ker­nel makes its rout­ing de­ci­sion. Packets ad­dressed to the ma­chine it­self travel up through INPUT. Packets ad­dressed to other hosts, when for­ward­ing is en­abled, move to FORWARD and then out through POSTROUTING. Every con­fig­u­ra­tion step ei­ther reg­is­ters code on one of these hooks or changes how the rout­ing de­ci­sion be­haves.

IP for­ward­ing is the first gate for en­abling trans­port of pack­ets across in­ter­faces. Without it, the FORWARD hook might ex­ist, but the ker­nel never sends pack­ets to it. Packets ar­riv­ing for for­eign des­ti­na­tions die af­ter the rout­ing lookup. With it open, the ker­nel hands those pack­ets to FORWARD, and every other piece of the router con­fig­u­ra­tion takes ef­fect.

You man­age ip for­ward­ing through the /etc/sysctl.d/10-forward.conf file:

/etc/sysctl.d/10-forward.conf

net.ipv4.ip_­for­ward=1

/etc/sysctl.d/ is a drop-in con­fig­u­ra­tion di­rec­tory for ker­nel run­time pa­ra­me­ters. At boot, sys­temd-sysctl.ser­vice reads every *.conf file in that di­rec­tory (plus /etc/sysctl.conf) and writes each pa­ra­me­ter to its cor­re­spond­ing path un­der /proc/sys/.

The ker­nel ex­poses a vir­tual filesys­tem at /proc/sys/ where every tune­able pa­ra­me­ter ap­pears as a file. The dot­ted sysctl no­ta­tion is just a path trans­la­tion: net.ipv4.ip_­for­ward maps to /proc/sys/net/ipv4/ip_forward. Writing 1 to this file tells the IPv4 stack to send pack­ets with non-lo­cal des­ti­na­tions through the FORWARD hook rather than dis­card­ing them. The ker­nel im­ple­ments this de­ci­sion in ip_­for­ward() in net/​ipv4/​ip_­for­ward.c.

Writing 1 to sysctl.d/​10-for­ward.conf makes those writes per­sis­tent across re­boots.

sys­temd-sysctl.ser­vice reads all files un­der /etc/sysctl.d/ at boot and ap­plies them in lex­i­co­graphic or­der. Restarting the ser­vice ap­plies them im­me­di­ately with­out re­quir­ing a sys­tem re­boot. You can ver­ify the ac­tive value at any time:

cat /proc/sys/net/ipv4/ip_forward

1 means for­ward­ing is live. 0 means the gate is closed, and the rest of the router con­fig­u­ra­tion is in­ert re­gard­less of what else is con­fig­ured.

Our first change is set­ting the ker­nel’s ip_­for­ward pa­ra­me­ter to 1.

A home net­work serves both wired and wire­less clients on the same sub­net. The con­fig­u­ra­tion cre­ates a net­work bridge, br0, and at­taches eth0 and wlan0 to it as mem­ber ports. For de­tails on Linux bridge in­ter­faces, see the ker­nel bridge doc­u­men­ta­tion.

Our sec­ond change is defin­ing a bridge and adding in­ter­faces to it that bind them for pass­ing pack­ets.

A bridge op­er­ates at Layer 2, the Ethernet layer. The ker­nel’s bridge mod­ule main­tains a Media Access Control (MAC) ad­dress for­ward­ing table. When a frame ar­rives on eth0, the bridge looks up the des­ti­na­tion MAC ad­dress in that table and for­wards the frame to the port where that ad­dress was last seen. If the ad­dress is un­known, the bridge floods the frame to all mem­ber ports. The bridge ex­pires learned as­so­ci­a­tions af­ter a con­fig­urable ag­ing time. To the rest of the net­work, br0 ap­pears as a sin­gle uni­fied switch, one shared Layer 2 seg­ment across both wired and wire­less in­ter­faces. The ker­nel im­ple­ments bridge for­ward­ing logic in br_­for­ward() in net/​bridge/​br_­for­ward.c.

This mat­ters for rout­ing be­cause the ker­nel as­signs IP ad­dresses to in­ter­faces, not to phys­i­cal ports. Assigning 192.168.1.1 to br0 means the router holds a sin­gle Local Area Network (LAN) ad­dress re­gard­less of whether a client is wired or wire­less. Both in­ter­faces carry traf­fic on the same sub­net and com­mu­ni­cate at Layer 2 with­out any rout­ing de­ci­sion re­quired be­tween them.

One im­por­tant dis­tinc­tion: a wired in­ter­face like eth0 is en­slaved to the bridge di­rectly with a sin­gle com­mand (ip link set eth0 mas­ter br0), and the ker­nel’s bridge mod­ule im­me­di­ately be­gins learn­ing MAC ad­dresses from frames ar­riv­ing on it. A wire­less in­ter­face (wlan0) can­not be en­slaved to the bridge this way.

The 802.11 pro­to­col re­quires an as­so­ci­a­tion and au­then­ti­ca­tion life­cy­cle that stan­dard Ethernet bridg­ing does­n’t ac­count for. Instead, hostapd man­ages this re­la­tion­ship: the bridge=br0 di­rec­tive in hostapd.conf in­structs hostapd to at­tach wlan0 to the bridge once the in­ter­face is in AP mode. Wireless clients that as­so­ci­ate with the AP are then vis­i­ble to the bridge as if they were on a wired port. The re­sult is the same uni­fied L2 seg­ment, but the path to get there is dif­fer­ent for wired and wire­less mem­bers.

The mac80211 sub­sys­tem moves all as­pects of mas­ter mode into user space. It de­pends on hostapd to han­dle au­then­ti­cat­ing clients, set­ting en­cryp­tion keys, es­tab­lish­ing key ro­ta­tion pol­icy, and other as­pects of the wire­less in­fra­struc­ture. Due to this, the old method of is­su­ing iw­con­fig  no longer works

On a stan­dard Ethernet bridge port, any de­vice that sends a frame gets its MAC learned — there’s no prior hand­shake re­quired at L2. On an 802.11 AP, the MAC layer it­self en­forces that a client must com­plete au­then­ti­ca­tion and as­so­ci­a­tion (State 3) be­fore the AP will ac­cept or for­ward its data frames. The AP’s MAC (managed by the dri­ver via mac80211) is the gate­keeper, and it needs a user­space dae­mon (hostapd) to han­dle the au­then­ti­ca­tion ex­changes. The ker­nel’s bridge mod­ule has no knowl­edge of 802.11 states — it just sees frames — so it can’t man­age this life­cy­cle on its own.

The bridge-utils pack­age pro­vides brctl for in­spect­ing bridge state. The ker­nel han­dles all for­ward­ing logic through the br_net­fil­ter and bridge mod­ules.

Aside: bridges and packet cap­ture. A bridge port is an ex­cel­lent place to in­sert a packet cap­ture. Attach a third in­ter­face to br0 and mir­ror traf­fic to a tap de­vice (for more on tap/​tun vir­tual in­ter­faces, see the ker­nel tun­tap doc­u­men­ta­tion), or use a stand­alone bridge with a port set to promis­cu­ous mode feed­ing a cap­ture dae­mon like tcp­dump or Zeek. Because the bridge sees all frames on the seg­ment be­fore any rout­ing or fil­ter­ing de­ci­sion, a cap­ture at this layer sees the com­plete pre-Net­work Address Translation (NAT), pre-fire­wall traf­fic pic­ture. Tools like tcp­dump -i br0 or an AF_PACKET socket bound to the bridge in­ter­face work at line rate for most home and small-busi­ness traf­fic vol­umes. These tools max out on a de­fault Linux ker­nel at around 18 Gbps (at least they did when I last tested them, around 2023). Higher line rates re­quire tools with hard­ware-based fil­ter­ing like the Data Plane Development Kit (DPDK) or eX­press Data Path (XDP).

Now that we have a bridge, we need to de­fine packet pro­cess­ing rules via net­fil­ter’s nfta­bles.

Netfilter is the broader ker­nel-level packet fil­ter­ing frame­work that pro­vides the hooks into the net­work stack, while nfta­bles (via nf_ta­bles) is the mod­ern packet clas­si­fi­ca­tion en­gine that op­er­ates on top of those hooks. It re­placed ipt­a­bles as the pre­ferred in­ter­face, but both ul­ti­mately rely on the same net­fil­ter hook in­fra­struc­ture in the ker­nel. The ker­nel im­ple­ments the nf_ta­bles sub­sys­tem in nf_ta­bles_api.c in net/​net­fil­ter/.

The fire­wall and NAT rules in /etc/nftables.conf are call­back reg­is­tra­tions. nfta­bles sends them to the ker­nel through a netlink socket, and the nf_ta­bles sub­sys­tem in­stalls them at the spec­i­fied hooks. Each chain de­c­la­ra­tion names its hook and pri­or­ity ex­plic­itly:

chain for­ward {

type fil­ter hook for­ward pri­or­ity 0; pol­icy drop;

iif­name “eth0” oif­name “br0″ ct state { es­tab­lished,re­lated } counter ac­cept

iif­name “br0” oif­name “eth0″ ct state { new,es­tab­lished,re­lated } counter ac­cept

counter

This chain con­trols traf­fic for­ward­ing be­tween in­ter­faces, the core job of a router. Here’s what’s hap­pen­ing:

This at­taches to net­fil­ter’s for­ward hook, mean­ing it only sees pack­ets that aren’t des­tined for the router it­self but need to pass through it. The de­fault pol­icy is drop, so any­thing not ex­plic­itly al­lowed is silently dis­carded. This is a deny-by-de­fault pos­ture.

In this WiFi AP setup, eth0 is the WAN-facing in­ter­face — the up­link to your ISP or up­stream router. br0 is the LAN-facing bridge, which ag­gre­gates traf­fic from wired clients (if any are di­rectly at­tached) and wire­less clients man­aged by hostapd. All LAN traf­fic en­ters and ex­its through br0, re­gard­less of whether it orig­i­nated from a wired or wire­less de­vice. With that topol­ogy in mind, the two rules in the FORWARD chain map di­rectly to the two di­rec­tions of traf­fic flow across the router.

Traffic ar­riv­ing from eth0 (the WAN/internet side) head­ing to­ward br0 (the LAN bridge) is only ac­cepted if con­ntrack (ct state) shows the con­nec­tion was al­ready ini­ti­ated from the LAN side. This means un­so­licited in­bound con­nec­tions from the in­ter­net are blocked, ex­actly what you want from a NAT router/​fire­wall.

Traffic from br0 head­ing out to eth0 is ac­cepted for new con­nec­tions as well as ex­ist­ing ones. This lets LAN clients freely ini­ti­ate con­nec­tions to the in­ter­net.

This is a catch-all counter with no ac­tion; it just counts pack­ets that matched nei­ther rule above (and will there­fore be dropped by the pol­icy). It’s use­ful for mon­i­tor­ing how much traf­fic is be­ing re­jected.

This is a clas­sic “stateful” fire­wall pat­tern. LAN de­vices can reach the in­ter­net freely, but the in­ter­net can never ini­ti­ate con­nec­tions in­ward. The re­lated state also al­lows things like Internet Control Message Protocol (ICMP) er­rors and File Transfer Protocol (FTP) data chan­nels that are as­so­ci­ated with an ex­ist­ing con­nec­tion to pass through.

When nfta­bles.ser­vice loads or re­loads the con­fig­u­ra­tion, it flushes the ex­ist­ing rule­set and in­stalls the new one atom­i­cally through the netlink in­ter­face. No packet sees a par­tial rule­set dur­ing the tran­si­tion. Reload with:

sudo sys­tem­ctl re­load nfta­bles.ser­vice

sudo nft -c -f /etc/nftables.conf

If you are gonna dive deep into net­fil­ter, this blog is out­stand­ing

Our third change was defin­ing nf_ta­bles rules for pro­cess­ing pack­ets.

The rule frag­ments ct state { es­tab­lished, re­lated } and ct state { new, es­tab­lished, re­lated } ref­er­ence con­ntrack, the ker­nel’s con­nec­tion track­ing sub­sys­tem. Conntrack is what makes two sim­ple rules suf­fi­cient to han­dle all le­git­i­mate traf­fic. The ker­nel im­ple­ments the con­nec­tion track­ing core in nf_­con­ntrack­_­core.c in net/​net­fil­ter/.

Conntrack watches traf­fic as it passes through net­fil­ter and main­tains a table of ac­tive flows. Each en­try stores the source and des­ti­na­tion ad­dresses, ports, pro­to­col, and cur­rent con­nec­tion state. When a LAN client opens a Transmission Control Protocol (TCP) con­nec­tion to a server on the in­ter­net, con­ntrack cre­ates an en­try and marks the flow new. Once the three-way hand­shake com­pletes, con­ntrack marks it es­tab­lished. Reply pack­ets from the in­ter­net match ct state es­tab­lished in the FORWARD chain and pass through au­to­mat­i­cally.

The fire­wall al­lows out­bound con­nec­tions from br0 to eth0 when they carry state new or es­tab­lished. Return pack­ets ar­riv­ing on eth0 match as es­tab­lished. Conntrack holds the book­keep­ing; the fire­wall rules con­sult the table.

The re­lated state cov­ers sec­ondary flows. Protocols like FTP open a con­trol con­nec­tion and then ne­go­ti­ate a sep­a­rate data con­nec­tion on a dif­fer­ent port. ICMP er­ror mes­sages tie back to ex­ist­ing TCP or User Datagram Protocol (UDP) flows. Conntrack un­der­stands these re­la­tion­ships and marks the sec­ondary flows ac­cord­ingly, so the fire­wall ac­cepts them with­out ex­plicit rules for every pro­to­col vari­ant.

Our fourth change is an ex­pan­sion of net­work con­nec­tion track­ing in the Kernel’s con­nec­tion track­ing sub­sys­tem. We have be­gun track­ing pack­ets for sys­tems be­yond just our own host.

Home net­works use Request for Comments (RFC) 1918 pri­vate ad­dress space: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. The pub­lic in­ter­net car­ries routes to none of these ranges. Every packet leav­ing the LAN needs its source ad­dress re­placed with the router’s pub­lic IP be­fore it ex­its. Without that re­place­ment, the orig­i­nat­ing host will never re­ceive replies from the in­ter­net.

The postrout­ing chain at the POSTROUTING hook re­places each out­bound pack­et’s pri­vate source ad­dress with the router’s pub­lic ad­dress:

chain postrout­ing {

type nat hook postrout­ing pri­or­ity 100; pol­icy ac­cept;

oif­name “eth0” counter mas­quer­ade

The term mas­quer­ade re­lates to the act of dis­guis­ing one­self. The router pre­tends to be the orig­i­nal sender of a re­quest bound for the in­ter­net, but it re­mem­bers which node on the in­ter­nal net­work made the orig­i­nal re­quest. The re­source on the in­ter­net re­sponds to the router as if it’s con­nect­ing with the orig­i­nal sender, but the router mod­i­fies the packet and sends it on to the orig­i­nal re­quester. The router pre­sents the LAN client to the out­side world un­der a dif­fer­ent iden­tity, the WAN IP, con­ceal­ing the pri­vate ad­dress be­hind a pub­lic one. The client ap­pears to the re­mote server as the router it­self. The router hides the clien­t’s orig­i­nal ad­dress. The ker­nel im­ple­ments the mas­quer­ade ac­tion in nf_­nat_­mas­quer­ade.c in net/​net­fil­ter/.

Conntrack stores the trans­la­tion as part of each flow’s en­try. The tu­ple (private IP, pri­vate port, pub­lic IP, pub­lic port, pro­to­col) lives in the con­ntrack table for the life­time of the con­nec­tion. You can in­spect it di­rectly:

sudo con­ntrack -L

Each line shows the orig­i­nal and re­ply tu­ples for a live flow, along with the con­nec­tion state and a time­out count­down. Flows that have been idle long enough age out, and con­ntrack re­moves their en­tries, a key mech­a­nism for pre­vent­ing the NAT table from grow­ing with­out bound. TCP con­nec­tions time out af­ter the ses­sion closes or af­ter a con­fig­urable idle pe­riod. UDP en­tries use shorter timers be­cause UDP car­ries no close sig­nal.

The mas­quer­ade ac­tion reads eth0’s cur­rent IP ad­dress at the mo­ment the packet is processed, rather than at con­fig­u­ra­tion time. This makes it the cor­rect choice for a WAN in­ter­face that ac­quires its ad­dress via Dynamic Host Configuration Protocol (DHCP), where the pub­lic IP may change with­out no­tice. When the ad­dress changes, new con­nec­tions use the new ad­dress au­to­mat­i­cally. Conntrack re­tains en­tries for es­tab­lished con­nec­tions un­der the old ad­dress un­til they ex­pire.

Our fifth change is defin­ing rules that mod­ify the sender and re­cip­i­ent ad­dresses in pack­ets processed by the host.

Every com­puter on the Internet needs to know three things to work: their IP ad­dress, their de­fault gate­way to the in­ter­net, and their Domain Name System (DNS) server.

A router must in­tro­duce it­self to clients on their net­work. New clients ar­rive with­out an IP ad­dress, with­out a de­fault gate­way, and with­out a DNS re­solver. dns­masq vends these val­ues to clients on their net­work through DHCP.

When a de­vice joins the net­work, it broad­casts a DHCP dis­cov­ery. dns­masq lis­tens on br0 and re­sponds with an of­fer con­tain­ing an IP ad­dress, sub­net mask, lease du­ra­tion, and two DHCP op­tions: op­tion 3 (default gate­way, 192.168.1.1) and op­tion 6 (DNS server, 192.168.1.1). Option 3 tells the client where to send pack­ets des­tined for ad­dresses out­side the lo­cal sub­net. Option 6 tells the client which re­solver to query. dns­masq caches up­stream re­sponses lo­cally, re­duc­ing query vol­ume and ac­cel­er­at­ing re­peat lookups.

dns­masq binds to br0 so it serves only the LAN. It never lis­tens on eth0.

NetworkManager as an al­ter­na­tive: NetworkManager can han­dle both DHCP server and DNS func­tions through its built-in dns­masq in­te­gra­tion, ac­ti­vated by set­ting dns=dns­masq in /etc/NetworkManager/NetworkManager.conf. NetworkManager launches its own dns­masq in­stance and man­ages its con­fig­u­ra­tion dy­nam­i­cally as in­ter­faces come and go.

There are sig­nif­i­cant trade­offs for each ap­proach. NetworkManager’s ap­proach re­duces man­ual con­fig­u­ra­tion and han­dles in­ter­face life­cy­cle events au­to­mat­i­cally. This is use­ful on a lap­top or a ma­chine where in­ter­faces ap­pear and dis­ap­pear. On a ded­i­cated router, you gen­er­ally will want greater con­trol. NetworkManager may re­con­fig­ure dns­masq or restart it in re­sponse to net­work events, in­ter­rupt­ing DHCP leases in un­pre­dictable ways. A sta­tic dns­masq con­fig­u­ra­tion launched by sys­temd gives you de­ter­min­is­tic startup or­der, ex­plicit bind­ing, and straight­for­ward log in­spec­tion via jour­nalctl -eu dns­masq.ser­vice. You know ex­actly what the dae­mon is con­fig­ured to do be­cause you wrote the con­fig­u­ra­tion file.

From a ker­nel per­spec­tive, both paths land in the same place: a user­space process bound to a UDP socket on port 67, ser­vic­ing DHCP re­quests ar­riv­ing on the bridge in­ter­face. The ker­nel does­n’t dis­tin­guish be­tween the two arrange­ments. The dif­fer­ence is in how the dae­mon is launched, con­fig­ured, and su­per­vised. This is a ser­vice man­age­ment and op­er­a­tional trade­off, not an ar­chi­tec­tural one.

Our sixth change is de­ploy­ing a new dae­mon (dnsmasq) for vend­ing DHCP and DNS ser­vices to clients on the sys­tem’s net­work(s).

Wireless in­ter­faces op­er­ate in one of sev­eral modes. In man­aged mode, a card scans for ac­cess points and as­so­ci­ates as a client. In AP mode, the card broad­casts bea­cons, ac­cepts as­so­ci­a­tion re­quests, and man­ages the full au­then­ti­ca­tion life­cy­cle for con­nect­ing de­vices.

The ker­nel’s mac80211 sub­sys­tem pro­vides a uni­fied pro­gram­ming in­ter­face for 802.11 hard­ware across dif­fer­ent dri­ver im­ple­men­ta­tions. hostapd com­mu­ni­cates with mac80211 through the nl80211 netlink in­ter­face, the same socket-based ker­nel-user­space chan­nel that nfta­bles uses, ap­plied here to the wire­less sub­sys­tem. Through nl80211, hostapd com­mands the dri­ver to en­ter AP mode, sets the Service Set Identifier (SSID), chan­nel, and Wi-Fi Protected Access 2 (WPA2) en­cryp­tion pa­ra­me­ters, and takes own­er­ship of au­then­ti­ca­tion frames.

The bridge=br0 di­rec­tive in hostapd.conf at­taches the AP in­ter­face to the bridge as a mem­ber port. Wireless clients, once as­so­ci­ated, en­ter the same Layer 2 seg­ment as wired clients. Their traf­fic ar­rives on br0, the ker­nel ap­plies the same net­fil­ter de­ci­sions, and pack­ets travel the same for­ward­ing path as every­thing else on the LAN.

Debian ships hostapd masked by de­fault. Systemd reg­is­ters the ser­vice but blocks it from start­ing. This block­ing pre­vents an un­con­fig­ured in­stance from launch­ing and broad­cast­ing an open net­work. sys­tem­ctl un­mask hostapd re­moves that block, af­ter which sys­tem­ctl en­able –now hostapd starts it and reg­is­ters it for fu­ture boots.

Our sev­enth change is de­ploy­ing a new dae­mon (hostapd) for vend­ing WiFi net­works from the de­vice’s WiFi card.

Each con­fig­u­ra­tion step ac­ti­vates a dif­fer­ent layer of the ker­nel’s net­work­ing ar­chi­tec­ture. Together, they build a com­plete for­ward­ing sys­tem:

Note on the bridge row: Adding a wired in­ter­face to br0 is a di­rect ker­nel op­er­a­tion — the bridge mod­ule im­me­di­ately takes over frame for­ward­ing for that port. Adding a wire­less in­ter­face is in­di­rect: hostapd’s bridge=br0 di­rec­tive han­dles the at­tach­ment af­ter the wire­less card en­ters AP mode and a client as­so­ci­ates. Both re­sult in the same log­i­cal L2 seg­ment, but the mech­a­nism dif­fers. If you are de­bug­ging bridge mem­ber­ship, brctl show (or ip link show mas­ter br0) will show wired mem­bers di­rectly; wire­less clients ap­pear as learned MAC en­tries in the bridge’s for­ward­ing table once they as­so­ci­ate, which you can in­spect with brctl show­macs br0.

Start with a Linux ma­chine in its de­fault state: a work­sta­tion that re­ceives pack­ets for it­self, for­wards noth­ing, and drops traf­fic ad­dressed to any IP it does­n’t own. Its IP for­ward­ing gate is closed. Its net­fil­ter FORWARD chain is empty. Its wire­less card lis­tens for bea­cons rather than broad­cast­ing them. It has no DHCP server, no NAT table, and no bridge.

* IP for­ward­ing opens the gate for the pos­si­bil­ity of rout­ing.

* The bridge col­lapses the wired and wire­less in­ter­faces into a sin­gle ad­dress­able do­main.

* The nfta­bles chains in­stall pol­icy at the FORWARD hook, de­cid­ing what passes and what drops.

* Conntrack feeds state in­for­ma­tion into those pol­icy de­ci­sions, mak­ing sim­ple rules work for com­plex traf­fic pat­terns.

* Masquerade hides the LAN be­hind the router’s pub­lic iden­tity and keeps a trans­la­tion table in mem­ory.

* dns­masq an­nounces the router’s pres­ence and hands every new client the in­for­ma­tion it needs to reach the out­side world.

These are the changes that trans­form a Linux sys­tem into a WiFi router. You can eval­u­ate and in­spect them through 6 com­mands: