[Bug] The 2.6.0 new version of tun forwarding has issues.

[mohaoho]

Verify steps

• Is this something you can debug and fix? Send a pull request! Bug fixes and documentation fixes are welcome.
• I have searched on the issue tracker for a related issue.

Version

tun2socks-2.6.0 linux/amd64, go1.25.0, 8fe7561

What OS are you seeing the problem on?

No response

Description

Testing under the same system：
Ubuntu 24.04.3 LTS (GNU/Linux 6.8.0-85-generic x86_64)

================================================================
This version cannot be forwarded properly

/usr/local/bin/tun2socks -version
tun2socks-2.6.0
linux/amd64, go1.25.0, 8fe7561

log：
sudo tcpdump -i tunruser20 -n
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on tunruser20, link-type RAW (Raw IP), snapshot length 262144 bytes
13:03:08.382771 IP 10.200.0.15 > 8.8.8.8: ICMP echo request, id 18241, seq 322, length 36
13:03:09.383864 IP 10.200.0.15 > 8.8.8.8: ICMP echo request, id 18241, seq 323, length 36
13:03:10.375319 IP 10.200.0.15 > 8.8.8.8: ICMP echo request, id 18241, seq 324, length 36
13:03:11.380413 IP 10.200.0.15 > 8.8.8.8: ICMP echo request, id 18241, seq 325, length 36
13:03:12.377687 IP 10.200.0.15 > 8.8.8.8: ICMP echo request, id 18241, seq 326, length 36
13:03:13.380955 IP 10.200.0.15 > 8.8.8.8: ICMP echo request, id 18241, seq 327, length 36

================================================================

This version can be forwarded normally

/usr/local/bin/tun2socks -version
（This version was compiled in May：-rwxr-xr-x 1 root root 10821780 May 25 15:19 /usr/local/bin/tun2socks）
tun2socks-2.6.0-beta
linux/amd64, go1.24.2, 44f7044

log：
sudo tcpdump -i tunruser20 -n
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on tunruser20, link-type RAW (Raw IP), snapshot length 262144 bytes
13:03:24.666819 IP 10.200.0.15 > 8.8.8.8: ICMP echo request, id 18241, seq 386, length 36
13:03:24.666996 IP 8.8.8.8 > 10.200.0.15: ICMP echo reply, id 18241, seq 386, length 36
13:03:25.667226 IP 10.200.0.15 > 8.8.8.8: ICMP echo request, id 18241, seq 386, length 36
13:03:25.667406 IP 8.8.8.8 > 10.200.0.15: ICMP echo reply, id 18241, seq 386, length 36
13:03:26.660682 IP 10.200.0.15 > 8.8.8.8: ICMP echo request, id 18241, seq 386, length 36
13:03:26.660853 IP 8.8.8.8 > 10.200.0.15: ICMP echo reply, id 18241, seq 386, length 36

Both versions can connect normally：
root@ubuntu:~# curl --interface tunruser20 https://ipinfo.io
{
"ip": "8.21*..",
"city": "Hong Kong",
"region": "Hong Kong",
"country": "HK",
"loc": "",
"org": "A.",
"postal": "*****",
"timezone": "Asia/Hong Kong",
"readme": "https://ipinfo.io/missingauth"
}

CLI or Config

No response

Logs

How to Reproduce

No response